Outward venting of inflow tracer in production wells

ABSTRACT

A localized inflow tracer ( 112 ) may be flushed from a gravel pack ( 104 ) surrounding a base pipe ( 102 ) of a production well by outwardly venting the inflow tracer. The base pipe ( 102 ) may include a non-perforated section ( 106 ) disposed adjacent to one or more perforated sections ( 108 ). A tracer carrier ( 110 ) may be disposed circumferentially about at least a portion of the non-perforated section ( 106 ) of the base pipe ( 102 ). An inflow tracer ( 112 ) may be released from the tracer carrier ( 110 ) into production fluid within the gravel pack ( 104 ) proximate to the non-perforated section ( 106 ) of the base pipe ( 102 ) such that the inflow tracer is flushed from the gravel pack ( 104 ) into individual ones of the one or more perforated sections ( 108 ) of the base pipe ( 102 ) and transported with the production fluid. The inflow tracer ( 112 ) may be prevented from being flushed directly from the tracer carrier ( 110 ) into the base pipe ( 102 ) due to a lack of permeability of the non-perforated section of the base pipe ( 102 ).

FIELD OF THE DISCLOSURE

The disclosure relates to systems and methods facilitating outwardventing of inflow tracer in a production well such that inflow tracer isprevented from being communicated directly into a base pipe of theproduction well from a tracer medium configured to emit the inflowtracer.

BACKGROUND

Different tracers have been widely used by the oil industry inproduction wells to identify which zones are contributing and/or otherinformation associated with a well. There are many types of tracercompounds and/or chemicals that can be used. The design and selection ofa given tracer may be based upon health, safety, and/or environmentrequirements; reservoir and/or fluid properties; expected operatingconditions; and/or other factors. Exemplary purposes of using tracersinstalled within tracer carrier systems of production wells include oneor more of determining an estimate of a contributing length, inflowprofile of oil, specific location(s) of water breakthrough, and/or otherpurposes. Such information helps to understand the reservoir andwaterflood performance.

Once a tracer has been installed in a well, it may be possible tocollect samples either after a short shut down or during steady stateproduction to analyze the well performance. This information can be usedto improve an understanding of reservoir properties, such as depletionand permeability, from pressure build up analysis. An opportunity tosample may arise when water breakthrough occurs. The results of thisanalysis can help to identify the location of water breakthrough andunderstand the waterflood performance in the reservoir.

Gravel packing of completions is necessary in some sand controlenvironments. Typically gravel packing is used when the uniformity andsorting of the sand grains in the reservoir rock is not favorable andwhere reliable long-term performance is required. Conventionally,tracers are installed inside a sand screen, which means the tracers candiffuse into the base pipe (i.e., inward venting). An inward ventedsystem allows the tracer to diffuse into the base pipe during a shutdown and in normal steady conditions. As such, the tracers can bedetected at Earth's surface regardless of the region where the tracersare installed. In addition, the space between the sand screen mesh andthe outer shroud may be very small meaning that many sand screens mightneed to be filled with tracers to meet the desired objectives of usingthe tracers. With existing approaches, estimating the contributinglength can be very difficult as there are always tracers at the surfacewhile another part of the well is contributing upstream of the tracerlocation. Furthermore, the spatial resolution of existing approaches isgenerally several tens of meters.

SUMMARY

One aspect of the disclosure relates to a system configured tofacilitate flushing a localized inflow tracer from a gravel packsurrounding a base pipe of a production well by outwardly venting theinflow tracer. The system comprises a base pipe and tracer carrier. Thebase pipe is configured to be disposed within a gravel pack. The basepipe includes a non-perforated section disposed adjacent to one or moreperforated sections. Individual ones of the one or more perforatedsections are configured to communicate production fluid from the gravelpack into the base pipe to facilitate transporting the production fluidto Earth's surface. The tracer carrier is configured to be disposedcircumferentially about at least a portion of the non-perforated sectionof the base pipe. The tracer carrier is further configured to carry atracer material. The tracer material is configured to release an inflowtracer into production fluid within the gravel pack proximate to thenon-perforated section of the base pipe such that the inflow tracer isflushed from the gravel pack into individual ones of the one or moreperforated sections of the base pipe and transported with the productionfluid. The non-perforated section of the base pipe substantiallyprevents release of the tracer directly from the tracer carrier towithin the base pipe.

Another aspect of the disclosure relates to a method for constructing asystem configured to facilitate flushing a localized inflow tracer froma gravel pack surrounding a base pipe of a production well by outwardlyventing the inflow tracer. The method comprises disposing a tracermaterial circumferentially about at least a portion of a non-perforatedsection of a base pipe configured to be disposed within a gravel pack.The non-perforated section of the base pipe is adjacent to one or moreperforated sections of the base pipe. Individual ones of the one or moreperforated sections are configured to communicate production fluid fromthe gravel pack into the base pipe to facilitate transporting theproduction fluid to Earth's surface. The tracer material is configuredto release an inflow tracer. The method comprises surrounding the tracermaterial with a perforated shroud configured to communicate the inflowtracer from the tracer material into production fluid within the gravelpack proximate to the non-perforated section of the base pipe such that,in use, the inflow tracer is flushed from the gravel pack intoindividual ones of the one or more perforated sections of the base pipeand transported with the production fluid.

Yet another aspect of the disclosure relates to a method for flushing alocalized inflow tracer from a gravel pack surrounding a base pipe of aproduction well. The method comprises installing a base pipe such thatthe base pipe is disposed within a gravel pack. The base pipe includes anon-perforated section disposed adjacent to one or more perforatedsections. Individual ones of the one or more perforated sections areconfigured to communicate production fluid from the gravel pack into thebase pipe to facilitate transporting the production fluid to Earth'ssurface. The base pipe has a tracer carrier disposed circumferentiallyabout at least a portion of the non-perforated section of the base pipe.The tracer carrier is configured to carry a tracer material. The tracermaterial is configured to release an inflow tracer. The methodcomprises, during production, flushing the inflow tracer within thegravel pack into individual ones of the one or more perforated sectionsof the base pipe. The method comprises transporting the production fluidwith the flushed inflow tracers toward the Earth's surface via the basepipe.

These and other objects, features, and characteristics of the presentdisclosure, as well as the methods of operation and functions of therelated elements of structure and the combination of parts and economiesof manufacture, will become more apparent upon consideration of thefollowing description and the appended claims with reference to theaccompanying drawings, all of which form a part of this specification,wherein like reference numerals designate corresponding parts in thevarious figures. It is to be expressly understood, however, that thedrawings are for the purpose of illustration and description only andare not intended as a definition of the limits of the disclosure. Asused in the specification and in the claims, the singular form of “a”,“an”, and “the” include plural referents unless the context clearlydictates otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a system configured to facilitate outward venting ofinflow tracer such that inflow tracer is prevented from beingcommunicated directly into a base pipe of a production well from atracer medium configured to emit the inflow tracer, in accordance withone or more embodiments.

FIGS. 2A, 2B, 2C, and 2D illustrate a flush out process of a systemhaving outward vended inflow tracer, in accordance with one or moreimplementations.

FIG. 3 illustrates a method for constructing a system configured tofacilitate outward venting of inflow tracer such that inflow tracer isprevented from being communicated directly into a base pipe of aproduction well from a tracer medium configured to emit the inflowtracer, in accordance with one or more embodiments.

FIG. 4 illustrates a method for outwardly venting inflow tracer suchthat inflow tracer is prevented from being communicated directly into abase pipe of a production well from a tracer medium configured to emitthe inflow tracer, in accordance with one or more embodiments.

DETAILED DESCRIPTION

FIG. 1 illustrates a system 100 configured to facilitate outward ventingof inflow tracer such that inflow tracer is prevented from beingcommunicated directly into a base pipe of a production well from atracer medium configured to emit the inflow tracer, in accordance withone or more embodiments. An outward vented system may improve technicalanalysis of a production well as the inflow tracer is flushed from theregion surrounding the base pipe, which may include a gravel pack and/orother permeable material. For example, the manner in which the inflowtracer is flushed can help distinguish differences in inflow that wouldnot be seen with an inward vented system. As another example, someembodiments include a relatively short tracer carrier (e.g., about 5-10meters), which places the inflow tracer in a highly localized area.Existing approaches that place the tracer in a sand screen can result inthe tracer being spread across 50 or more meters of reservoir interval.Having the tracer placed in a concentrated area can refine specialresolution of the technical analysis and can allow for more tracer typesto be used. Furthermore, some embodiments facilitate use of tracershaving a relatively long lifetime.

As depicted in FIG. 1, system 100 includes a base pipe 102 configured tobe disposed within a gravel pack 104. In some embodiments, gravel pack104 forms an annulus about base pipe 102. The gravel pack 104 may bereplaced partially or wholly by one or more other permeable materials,according to some embodiments. The base pipe 102 includes anon-perforated section 106 disposed adjacent to one or more perforatedsections 108. The non-perforated section 106 of the base pipe 102 is notpermeable to liquid. The perforated sections 108 are configured tocommunicate production fluid from the gravel pack into the base pipe tofacilitate transporting the production fluid to Earth's surface. Theproduction fluid can include one or more of oil, water, and/or otherfluids.

The system 100 includes a tracer carrier 110, in accordance with someembodiments. The tracer carrier 110 is configured to be disposedadjacent to non-perforated section 106 of base pipe 102. In someembodiments, tracer carrier 110 is configured to be disposedcircumferentially about at least a portion of non-perforated section 106of base pipe 102. The tracer carrier 110 is configured to carry a tracermaterial 112. The tracer material 112 is configured to release inflowtracer into production fluid within a region of gravel pack 104proximate to non-perforated section 106 of base pipe 102. According tosome embodiments, inflow tracer is released by tracer material 112responsive to production flow and/or a component of the production fluidcoming into direct contact with tracer material 112.

In some embodiments, tracer carrier 110 comprises a perforated shroud114 configured to be disposed circumferentially about at least a portionof non-perforated section 106 of base pipe 102. A gap is formed betweenan inner diameter of perforated shroud 114 and non-perforated section106 of base pipe 102. The tracer material 112 is disposed within thegap. In some embodiments, tracer material 112 is wrapped aroundnon-perforated section 106 of base pipe 102. The perforated shroud 114is configured to communicate inflow tracer from tracer material 112 intothe production fluid within the gravel pack 104 proximate tonon-perforated section 106 of base pipe 102. According to variousembodiments, tracer carrier 110 has a longitudinal length less thanabout 10 meters, or even less than about 5 meters. In some embodiments,at least one slip ring 116 is disposed about non-perforated section 106of base pipe 102. The slip ring 116 is configured to establish a gapbetween non-perforated section 106 of base pipe 102 and an innerdiameter of perforated shroud 114. The tracer material 112 is disposedwithin the gap.

During production, inflow tracer is flushed from gravel pack 104 intoindividual ones of the one or more perforated sections 108 of base pipe102 and transported with the production fluid via base pipe 102. Theinflow tracer is prevented from being flushed directly from tracercarrier 110 into base pipe 102 due to a lack of permeability ofnon-perforated section 106 of base pipe 102. According to someembodiments, the inflow tracer flushed into base pipe 102 andtransported with the production fluid is detectable to determine one ormore characteristics associated with the production well. Exemplarycharacteristics include one or more of identification of contributingzones of a reservoir, reservoir depletion, reservoir permeability,production fluid properties, expected operating conditions, contributinglength, inflow profile of production fluid, location of waterbreakthrough, reservoir performance, waterflood performance, and/orother characteristics associated with the production well.

FIGS. 2A, 2B, 2C, and 2D illustrate a flush out process of a system 200having outward vended inflow tracer 202, in accordance with one or moreimplementations. The system 200 may be the same as or similar to system100 described in connection with FIG. 1. FIG. 2A illustrates system 200subsequent to shut in. Shut in describes when a production well is notproducing, but is capable of producing. Here, inflow tracer 202 isdistributed similar as during production.

FIG. 2B illustrates system 200 after a duration of time since shut in.Such a duration may be several hours or another amount of time. Thedepiction of system 200 in FIG. 2B assumes low flow activity in thegravel pack during shut in. During the shut-in period, inflow tracer 202is released into the production fluid surrounding the tracer carrier204, creating a high-concentration tracer shot as inflow tracer releaseis typically independent from the velocity of surrounding fluids.Generally, a concentration of inflow tracer within the base pipe remainsabout the same as for steady state production prior to shut in.

FIG. 2C illustrates system 200 when production has begun after theshut-in period. Arrows 206 indicate a direction of flow of theproduction fluid being transported by system 200. During initialproduction, the high-concentration tracer shot will be flushed outthrough the gravel pack into the base pipe. This flush-out may beobserved in technical analysis as a high-concentration peak of inflowtracer that declines over time. FIG. 2D illustrates system 200 after aperiod of stable production. Here, the concentration of inflow tracerstabilizes at a constant level.

For technical analysis, samples of the production fluid are taken at thesurface to determine the presence and/or concentration of a particularinflow tracer. The tracer response can be analyzed from the samples tounderstand how that particular inflow tracer was flushed out. Usingseveral different types of inflow tracers throughout the producinginterval(s) of the production well allows an understanding of the inflowresponse throughout the production well. The space or gap included inexemplary embodiments of the tracer carrier 110 allows for a relativelylarge amount of tracer material to be used so that the inflow tracer canlast for a period of time, which might extend to 5 or more years. Assuch, inflow tests can be repeated periodically to monitor the inflowcharacteristics with time, in accordance with some embodiments. It ispossible to identify “no flow” of the production fluid (i.e., a flowrate of zero) because inflow tracer will enter the base pipe if it isflushed by production fluid coming in from the reservoir through thegravel pack. Keeping the longitudinal length of the tracer carrierrelatively short (e.g., 5-10 meters) compared to existing approaches,where tracer material is distributed over lengths exceeding 30 meters,facilitates higher spatial resolution during technical analysis and/orallows for a greater number of different types of inflow tracer to beused, which may more clearly identify the location of a water breakthrough.

FIG. 3 illustrates a method 300 for constructing a system configured tofacilitate outward venting of inflow tracer such that inflow tracer isprevented from being communicated directly into a base pipe of aproduction well from a tracer medium configured to emit the inflowtracer, in accordance with one or more embodiments. The operations ofmethod 300 presented below are intended to be illustrative. In someembodiments, method 300 may be accomplished with one or more additionaloperations not described, and/or without one or more of the operationsdiscussed. Additionally, the order in which the operations of method 300are illustrated in FIG. 3 and described below is not intended to belimiting.

At an operation 302, a tracer material (e.g., tracer material 112) isdisposed circumferentially about at least a portion a non-perforatedsection (e.g., non-perforated section 106) of a base pipe (e.g., basepipe 102). According to some embodiments, disposing the carrier materialcircumferentially about at least a portion of the non-perforated sectionof the base pipe includes wrapping the carrier material around thenon-perforated section of the base pipe. The base pipe is configured tobe disposed within a gravel pack (e.g., gravel pack 104). The gravelpack may form an annulus about the base pipe, in some embodiments. Thenon-perforated section of the base pipe is adjacent to one or moreperforated sections (e.g., perforated sections 108) of the base pipe.Individual ones of the one or more perforated sections are configured tocommunicate production fluid from the gravel pack into the base pipe tofacilitate transporting the production fluid to Earth's surface. Thetracer material is configured to release an inflow tracer.

At an operation 304, at least one slip ring (e.g., slip ring 116) isdisposed about the non-perforated section of the base pipe. The at leastone slip ring is configured to establish a gap between thenon-perforated section of the base pipe and an inner diameter of aperforated shroud (e.g., perforated shroud 114). The tracer material isdisposed within the gap.

At an operation 306, the tracer material is surrounded with theperforated shroud. According to some embodiments, the perforated shroudhas a longitudinal length less than about 10 meters. The perforatedshroud is configured to communicate the inflow tracer from the tracermaterial into production fluid within the gravel pack proximate to thenon-perforated section of the base pipe. The inflow tracer is preventedfrom being flushed directly from the tracer carrier into the base pipedue to a lack of permeability of the non-perforated section of the basepipe.

FIG. 4 illustrates a method 400 for outwardly venting inflow tracer suchthat inflow tracer is prevented from being communicated directly into abase pipe of a production well from a tracer medium configured to emitthe inflow tracer, in accordance with one or more embodiments. Theoperations of method 400 presented below are intended to beillustrative. In some embodiments, method 400 may be accomplished withone or more additional operations not described, and/or without one ormore of the operations discussed. Additionally, the order in which theoperations of method 400 are illustrated in FIG. 4 and described belowis not intended to be limiting.

At an operation 402, a base pipe (e.g., base pipe 102) is installed suchthat the base pipe is disposed within a gravel pack (e.g., gravel pack104). The gravel pack may form an annulus about the base pipe, in someembodiments. The base pipe includes a non-perforated section (e.g.,non-perforated section 106) disposed adjacent to one or more perforatedsections (e.g., perforated sections 108). Individual ones of the one ormore perforated sections are configured to communicate production fluidfrom the gravel pack into the base pipe to facilitate transporting theproduction fluid to Earth's surface. The base pipe has a tracer carrier(e.g., tracer carrier 110) disposed circumferentially about at least aportion of the non-perforated section of the base pipe. The tracercarrier is configured to carry a tracer material (e.g., tracer material112). The tracer material is configured to release an inflow tracer.

At an operation 404, during shut in of the production well, the inflowtracer is allowed to become concentrated in the gravel pack proximate tothe non-perforated section of the base pipe.

At an operation 406, during production, the inflow tracer within thegravel pack is flushed into individual ones of the one or moreperforated sections of the base pipe. During initial production after ashut-it period, a high tracer concentration shot may be transported withthe production fluid when the inflow tracer is first flushed from thegravel pack. The inflow tracer is prevented from being flushed directlyfrom the tracer carrier into the base pipe due to a lack of permeabilityof the non-perforated section of the base pipe.

At an operation 408, the production fluid with the flushed inflow traceris transported toward the Earth's surface via the base pipe.

At an operation 410, the inflow tracer transported with the productionfluid is detected to determine one or more characteristics associatedwith the production well. Exemplary characteristics associated with theproduction well may include one or more of identification ofcontributing zones of a reservoir, reservoir depletion, reservoirpermeability, production fluid properties, expected operatingconditions, contributing length, inflow profile of production fluid,location of water breakthrough, reservoir performance, waterfloodperformance, and/or other characteristics.

Although the disclosure has been described in detail for the purpose ofillustration based on what is currently considered to be the mostpractical and preferred embodiments, it is to be understood that suchdetail is solely for that purpose and that the disclosure is not limitedto the disclosed embodiments, but, on the contrary, is intended to covermodifications and equivalent arrangements that are within the spirit andscope of the appended claims. For example, it is to be understood thatthe present disclosure contemplates that, to the extent possible, one ormore features of any embodiment can be combined with one or morefeatures of any other embodiment.

What is claimed is:
 1. A system configured to facilitate outward ventingof inflow tracer such that inflow tracer is prevented from beingcommunicated directly into a base pipe of a production well from atracer medium configured to emit the inflow tracer, the systemcomprising: a base pipe configured to be disposed within a gravel pack,the base pipe including a non-perforated section disposed adjacent toone or more perforated sections, individual ones of the one or moreperforated sections being configured to communicate production fluidfrom the gravel pack into the base pipe to facilitate transporting theproduction fluid to Earth's surface; and a tracer carrier configured tobe disposed circumferentially about at least a portion thenon-perforated section of the base pipe, the tracer carrier beingfurther configured to carry a tracer material, the tracer material beingconfigured to release inflow tracer into production fluid within thegravel pack proximate to the non-perforated section of the base pipesuch that, during production, the inflow tracer is flushed from thegravel pack into individual ones of the one or more perforated sectionsof the base pipe and transported with the production fluid, wherein thenon-perforated section of the base pipe substantially prevents releaseof the tracer directly from the tracer carrier to within the base pipe.2. The system of claim 1, wherein the inflow tracer is prevented frombeing flushed directly from the tracer carrier into the base pipe due toa lack of permeability of the non-perforated section of the base pipe.3. The system of claim 1, wherein the inflow tracer flushed into thebase pipe and transported with the production fluid is detectable todetermine one or more characteristics associated with the productionwell.
 4. The system of claim 3, wherein the one or more characteristicsassociated with the production well include one or more ofidentification of contributing zones of a reservoir, reservoirdepletion, reservoir permeability, production fluid properties, expectedoperating conditions, contributing length, inflow profile of productionfluid, location of water breakthrough, reservoir performance, orwaterflood performance.
 5. The system of claim 1, wherein the tracermaterial is wrapped around the non-perforated section of the base pipe.6. The system of claim 1, wherein the tracer carrier comprises aperforated shroud configured to be disposed circumferentially about atleast a portion of the non-perforated section of the base pipe, a gapbeing formed between an inner diameter of the perforated shroud and thenon-perforated section of the base pipe, the tracer material beingdisposed within the gap, the perforated shroud being further configuredto communicate the inflow tracer from the tracer material into theproduction fluid within the gravel pack proximate to the non-perforatedsection of the base pipe.
 7. The system of claim 1, wherein theproduction fluid includes one or both of oil or water.
 8. A method forconstructing a system configured to facilitate outward venting of inflowtracer such that inflow tracer is prevented from being communicateddirectly into a base pipe of a production well from a tracer mediumconfigured to emit the inflow tracer, the method comprising disposing atracer material circumferentially about at least a portion anon-perforated section of a base pipe configured to be disposed within agravel pack, the non-perforated section of the base pipe being adjacentto one or more perforated sections of the base pipe, individual ones ofthe one or more perforated sections being configured to communicateproduction fluid from the gravel pack into the base pipe to facilitatetransporting the production fluid to Earth's surface, the tracermaterial being configured to release an inflow tracer; and surroundingthe tracer material with a perforated shroud configured to communicatethe inflow tracer from the tracer material into production fluid withinthe gravel pack proximate to the non-perforated section of the base pipesuch that, during production, the inflow tracer is flushed from thegravel pack into individual ones of the one or more perforated sectionsof the base pipe and transported with the production fluid.
 9. Themethod of claim 8, wherein the inflow tracer is prevented from beingflushed directly from the tracer carrier into the base pipe due to alack of permeability of the non-perforated section of the base pipe. 10.The method of claim 8, wherein disposing the carrier materialcircumferentially about at least the portion of the non-perforatedsection of the base pipe includes wrapping the carrier material aroundat least the portion of the non-perforated section of the base pipe. 11.A method for outwardly venting inflow tracer such that inflow tracer isprevented from being communicated directly into a base pipe of aproduction well from a tracer medium configured to emit the inflowtracer, the method comprising: installing a base pipe such that the basepipe is disposed within a gravel pack, the base pipe including anon-perforated section disposed adjacent to one or more perforatedsections, individual ones of the one or more perforated sections beingconfigured to communicate production fluid from the gravel pack into thebase pipe to facilitate transporting the production fluid to Earth'ssurface, the base pipe having a tracer carrier disposedcircumferentially about at least a portion of the non-perforated sectionof the base pipe, the tracer carrier being configured to carry a tracermaterial, the tracer material being configured to release an inflowtracer; during production, flushing the inflow tracer within the gravelpack into individual ones of the one or more perforated sections of thebase pipe; and transporting the production fluid with the flushed inflowtracer toward the Earth's surface via the base pipe.
 12. The method ofclaim 11, wherein the inflow tracer is prevented from being flusheddirectly from the tracer carrier into the base pipe due to a lack ofpermeability of the non-perforated section of the base pipe.
 13. Themethod of claim 11, further comprising, during shut in of the productionwell, allowing the inflow tracer to become concentrated in the gravelpack proximate to the non-perforated section of the base pipe such that,when the inflow tracer is flushed from the gravel pack duringproduction, a high tracer concentration shot is transported with theproduction fluid.
 14. The method of claim 11, further comprisingdetecting the inflow tracer transported with the production fluid todetermine one or more characteristics associated with the productionwell.
 15. The method of claim 14, wherein the one or morecharacteristics associated with the production well include one or moreof identification of contributing zones of a reservoir, reservoirdepletion, reservoir permeability, production fluid properties, expectedoperating conditions, contributing length, inflow profile of productionfluid, location of water breakthrough, reservoir performance, orwaterflood performance.